The invention relates to the field of television audience research, and more particularly, to the detection of the viewing of television signals originating from a signal source within a statistically sampled household.
As disclosed by Thomas et al., in U.S. Pat. No. 5,481,294, which is assigned to the same assignee as the present invention and the disclosure of which is herein incorporated by reference, the signal (i.e., television or radio), that has been selected, and is being viewed or heard, by an audience member on a television or radio receiver in a statistically selected household, may be determined by ascertaining the channel to which the tuner of the television or radio is tuned. This channel information is stored locally for subsequent retrieval by a central data collection office. The central data collection office matches the retrieved channel information against a cable/station record which indicates which station corresponds to which channel and/or against a program record list of television or radio programs which were transmitted on that channel in order to determine the television or radio program that the audience member selected. As noted in U.S. Pat. No. 5,481,294 by Thomas et al., this process becomes cumbersome as the number of signal sources, the number of channels, the changes to channel mappings at a cable headend, and/or the number of television or radio programs increase, and can fail to produce usable data if there is an error in the program record list that provides the concordance between channels and programs.
Several approaches have been proposed that are intended to avoid the cumbersome cable/station record and/or program record list manner of keeping track of which station and/or which programming is available from which signal source and channel within a sampled household. As an example, one such approach has employed a program monitoring system that reads an identifying code embedded in the program, and uses the ancillary code to identify the program to which the television or radio was tuned.
As another example, a program signature is extracted from the program signal selected for use (i.e., for viewing if the signal is a television signal, or for listening if the signal is a radio signal) in the sampled household and is later compared to previously extracted reference signatures in an effort to match the program signature to a previously extracted reference signature in order to thereby identify the selected program. Accordingly, this signature approach is a correlation system which uses a sample frequency that is less than the frequency of the program signal.
Such monitoring equipment in the sampled household also stores a time stamp in addition to the ancillary code or program signature. The time stamp is used to determine the time and date of viewing and/or listening relative to the selected program.
Thomas et al., in U.S. Pat. No. 5,425,100, and U.S. Pat. No. 5,526,427, both of which are assigned to the same assignee as the present invention, teach a hierarchical, multi-level encoding system for identifying a transmitted program by reading an ancillary program identifying code which is sequentially added to the program as it passes through various stages of a program distribution network. The disclosures of U.S. Pat. No. 5,425,100 and U.S. Pat. No. 5,526,427 are hereby incorporated by reference. Other program monitoring systems employing ancillary codes which are embedded in a transmitted program are taught by Haselwood et al. in U.S. Pat. No. 4,025,851, and by Crosby in U.S. Pat. No. 3,845,391.
A program monitoring system that exclusively relies on ancillary codes may produce inaccurate results when ancillary codes are either intentionally or accidentally omitted from program signals. Even when the original program signal is encoded with an ancillary code, there is a risk that the ancillary code will be intentionally removed before the program signal is viewed or heard. There is also the risk that ancillary codes may be accidentally removed before the program in which they are embedded is viewed or heard. For example, ancillary codes that are embedded in video or audio program signals so that they are undetectable to a viewer or listener, or so that they are at least unobtrusive enough to be no more than minimally detectable by a viewer or listener, are commonly stripped from the video or audio program signals when the video or audio program signals are compressed (e.g., such as by the MPEG II compression scheme used with digital television signals).
Moreover, ancillary codes, which are inserted into vertical blanking intervals (VBI) of the video portions of program signals, and which survive passage through the signal transmission chain so as to be received by a user""s television receiver, are commonly removed from the video before the video is applied to the CRT of a television. As a result, non-intrusive acquisition of these VBI ancillary codes is impractical because such non-intrusive acquisition usually requires the use of probes which generally pick up the video sent by the tuner to the CRT after the VBI ancillary codes have already been stripped from the video.
Therefore, ancillary codes in the vertical blanking interval are more easily detected if the monitored television receiver is opened so that leads of the monitoring equipment can be soldered to video test points of the television receiver at which the ancillary codes are still present. However, such an arrangement is intrusive, leading to objections by the members of the statistically sampled households.
Signal comparison program monitoring systems, other than signature matching systems such as those described above, have also been used in order to determine the signal sources (e.g., channels) of the programs being viewed or heard. One of the oldest known signal comparison program monitoring systems compares a synchronization component of a television program signal selected by a television tuner with a corresponding synchronization component in a program signal selected by a reference tuner. This signal comparison program monitoring system credits viewing to the signal source selected by the reference tuner when and if the two synchronization components match within some predetermined error.
Currey, in U.S. Pat. No. 3,372,233, provided an early teaching of such a program monitoring system which compared the phasing of vertical synchronization signals for this purpose. Currey""s approach was not particularly successful because there are times when the vertical-synchronization components from different signal sources occasionally match. When this type of matching occurs, the program source measurement is ambiguous. Solar, in U.S. Pat. No. 4,764,808, and Gall, in U.S. Pat. No. 4,847,685, provided improved synchronization component measurement systems that did not entirely overcome the basic shortcoming of the Currey approach. In U.S. Pat. No. 5,294,977, Fisher et al. disclosed a synchronization component based measurement system operating in a restricted environment in which such phase coincidences can be avoided.
Another signal comparison program monitoring system correlates a receiver signal, which may be extracted from a receiver being monitored, with a reference signal, which may be supplied by a reference tuner that is tuned consecutively to the possible program signal sources to which the monitored receiver may be tuned. This correlation system determines the channel being viewed or heard when the correlation between the receiver signal from the monitored receiver and the reference signal from the reference tuner exceeds some predetermined value. This monitoring approach was initially adapted for the purpose of in-home identification of viewed television programs by Kiewit et al. in U.S. Pat. No. 4,697,209, the disclosure of which is herein incorporated by reference. The teachings of Kiewit et al. have been expanded upon by Thomas et al., in U.S. Pat. No. 5,481,294, who described the use of signatures extracted from either a video component or an audio component of a receiver signal, and who discussed the operational advantages of using non-invasive sensors to acquire the components.
A further comparison program monitoring system was placed in commercial service in 1984 by the A. C. Nielsen Company and was internally referred to as the Real Time Correlation (RTC) system. The RTC system used a combination of (i) vertical synchronization component matching and (ii) audio correlation in order to identify an unknown signal. The RTC system did so by first making a preliminary identification based upon matching of vertical synchronization components. However, this preliminary identification would not be unique if the unknown transmitted signal, for example, was one of several sync-locked signals originating at a local cable head-end. Therefore, the RTC system resolved ambiguities by correlating the audio component of the selected transmitted signal from the monitored television with the audio component of the reference signal from the reference tuner whose synchronization component matched the synchronization component of the transmitted signal.
Correlation program monitoring systems are generally more robust and less affected by signal degradation than are code reading program monitoring systems. Even so, a signal correlation program monitoring system, which compares two signals (e.g., a receiver signal selected by a monitored television at a television viewing site in a statistically sampled household, and a reference signal selected by a reference tuner at a different local reference site), works best when the two signals to be correlated are both high quality replicas of what was actually transmitted. If one of the correlated signals, such as the receiver signal selected by the monitored television, is acquired by a non-intrusive sensor at the television viewing site, and if the other correlated signal, such as the reference signal selected by the reference tuner, is acquired from the audio or video circuitry of a tuner at a different local reference site, artifacts introduced by the non-intrusive measurement at the television viewing site may have a substantial adverse impact on the correlation between the receiver and reference signals. To reduce such artifacts, Thomas et al., in the aforementioned U.S. Pat. No. 5,481,294, teach the suppression or removal of background noise from an audio signal acquired by a non-intrusive microphone at the receiver viewing or listening site.
Another problem facing signal correlation systems is that, because signal correlation systems require an ongoing collection of reference signatures by equipment dedicated to monitoring the signals transmitted from each program signal source in whatever regional market is being measured, the operating cost of a signature-based program monitoring system is generally higher than that of a comparable program monitoring system relying on ancillary codes.
A problem facing all, or nearly all, program monitoring systems arises from signal sources which originate within the household itself. Signal sources of this sort may include computers or video games, which use the monitored television""s display, and video cassette (or tape) recorders, which play program signals that were recorded at earlier times or that are recorded on rental cassettes (or tapes). The use of such local signal sources is, with one exception to be discussed below, systematically excluded from a long-established audience measurement parameter called xe2x80x9cHouseholds Using Televisionxe2x80x9d (HUT) because the use of a television receiver with a locally generated signal does not fall within the scope of conventional television audience measurements.
Moreover, if a local signal source is not identified as such, a program monitoring system could either (i) erroneously count viewing or listening based on this local signal source as it would count viewing or listening based upon a remote signal source, or (ii) label the viewing or listening based on the local signal source as an unidentified activity. Either way, viewing or listening based upon a local signal source would be included as contributions to the overall HUT value reported by the program monitoring system in such a way as to create ambiguities.
The exception mentioned above relates to recording of programs by VCRs for later time shifted viewing. The reportable HUT value generally counts time-shifting viewing either at the time of recording or at the time of playback, but does not count at both recording and playback. By not counting at both recording and playback, double counting is avoided. Also, whether counting is done at the time of recording or at the time of playback, program monitoring systems strive to count only transmitted programs and seek to avoid counting non-transmitted programs, such as rented movies.
Also, a VCR typically has a number of modes in a non-record mode. For example, in a monitor mode, the VCR is used to pass through a currently selected transmitted program signal so that the signal may be viewed on a television, but the VCR does not concurrently record the signal. In a tune/record mode, the VCR is used to pass through a currently selected transmitted program signal for both viewing and recording. In a non-tune/record mode, the VCR is used to record a program without concurrent viewing of the program on a television; thus, the program is recorded for time-shifted playing. In a play mode, the VCR is used to play transmitted materials, and as tune-shifted recordings, and non-transmitted materials, such as rented movies. In an off mode, the VCR is off. Because of this number of modes, a VCR presents one of the most difficult program monitoring challenges.
Early measurements of VCRs in sampled households involved monitoring of both the control switches and the tuners of VCRs. This monitoring resulted in the measurement of recording, which was credited to program ratings when recorded, and in the identification of all other uses as not contributing to program ratings. Thus, for example, when recording was counted as HUT viewing, all play activity was counted as non-HUT usage). These early measurements of VCRs involved a complicated and expensive disassembly and modification of consumers"" equipment in order to physically connect switch monitoring equipment to the VCR switches.
Subsequent improvements in VCR measurement provided less invasive, and in some cases entirely non-invasive, ways of acquiring the requisite signals. In U.S. Pat. No. 4,633,302, Damoci teaches a method of picking up an artifact from the output of a VCR""s erase-head in order to ascertain that the measured VCR is recording a tuned signal. Vitt et al., in U.S. Pat. No. 5,165,069, teach a further improved measurement method in which all the status information (including a sensed erase-head output, which is commonly selected by different manufacturers to be a continuous wave (CW) tone lying between thirty and seventy-five kHz) is acquired from a sensor or pickup located immediately adjacent to, but externally of, the VCR""s housing. The disclosure of Vitt et al. is herein incorporated by reference. Mostafa et al., in U.S. Pat. No. 5,495,282, teach yet another non-invasive arrangement for monitoring the operation of a VCR by injecting encoded identification signals into the VCR and searching for that signal in the RF output from the VCR. Yet the monitoring of VCRs continue to be a difficult problem.
The present invention solves one or more of the above-noted problems.
In accordance with one aspect of the present invention, a system for identifying a signal source supplying a program signal to a monitored receiver comprises program signature extracter and signal source identifier. The monitored receiver is located in a household. The program signature, extracter extracts a reference program signature representative of an output of the monitored receiver and extracts a source program signature representative of the program signal supplied by the signal source. The program signature extracter is located in the household. The signal source identifier identifies the signal source as a source of the program signal in response to the reference program signature and the source program signature.
In accordance with another aspect of the present invention, a system for identifying which of first and second signal sources is supplying a program signal to a monitored receiver comprises program signature extracter and signal source identifier. The first and second signal sources and the monitored receiver are located in a household. The program signature, extracter extracts a reference program signature representative of an output of the monitored. receiver and extracts first and second source program signatures representative of an output of the first and second signal sources. The program signature extracter is located in the household. The signal source identifier identifies which of the first and second signal sources is a source of the program signal in response to the reference program signature and the first and second source program signatures.
In accordance with yet another aspect of the present invention, a system for identifying a program tuned by a monitored receiver comprises a source tuner, a program signature extracter, a signature correlater, and a code reader. The monitored receiver is located in a household. The source tuner is separate from a tuner of the monitored receiver and tunes to programs tunable by the monitored receiver. The source tuner is located in a household. The program signature extracter is operably coupled to the monitored receiver and to source tuner, and extracts a first program signature from an output of the monitored receiver and a second program signature from an output of the source tuner. The signature correlater correlates the first and second program signatures. The code reader is operably coupled to the source tuner and reads an ancillary code from the output of source tuner if the signature correlater detects a match between the first and second program signatures.
In accordance with still another aspect of the present invention, a system for determining an operating mode of a recording/playing device comprises tuning means, first, second, third, and fourth signal acquiring means, and determining means. The recording/playing device generates a recording indicating signal during recording and operates in conjunction with a receiver. The tuning means is separate from a tuner of the receiver and tunes to a program signal. The first signal acquiring means acquires a first signal from an output of the recording/playing device. The second signal acquiring means acquires a second signal from an output of the tuning means. The third signal acquiring means acquires a third signal from an output of the receiver. The fourth signal acquiring means acquires the recording indicating signal. The determining means is coupled to the first, second, third, and fourth signal acquiring means and determines an operating mode of the recording/playing device dependent upon the first, second, and third signals and the recording indicating signal.
In accordance with a further aspect of the present invention, a system for measuring the use of a video recorder operably connected to a television receiver comprises source tuning means, television receiver signal acquiring means, and first and second comparing means. The television receiver receives a plurality of transmitted television signals. The source tuning means tunes to a source program signal corresponding to a transmitted television signal. The television receiver signal acquiring means acquires a signal displayed on the television receiver. The first comparing means compares a signal from the video recorder to the source program signal. The second comparing means compares the signal from the video recorder to the signal acquired by the television receiver signal acquiring means.
In accordance with yet a further aspect of the present invention, a method of determining the source of a signal selected for use by a user at a monitored receiver in a household comprises the steps of: (a) selecting, by means of a source receiver, a source signal corresponding to a channel; (b) acquiring, by use of a non-intrusive sensor disposed proximate to the monitored receiver, a representation of the signal selected by the user; (c) comparing the representation of the signal selected by the user to the source signal in order to determine a difference between the representation and the source signal; (d) if the difference is less than a predetermined amount, identifying the representation as the source signal; (e) if the difference is not less than a predetermined amount, controlling the source receiver to receive a source signal corresponding to another channel and repeating steps (c) and (d).
In accordance with a still further aspect of the present invention, a method of reading an ancillary code operably associated with a user selected program signal transmitted from one of a plurality of program channels to which a household receiver in a household is tuned comprises the steps of: (a) acquiring the user selected program signal from the household receiver; (b) acquiring a source program signal from a predetermined one of the plurality of program channels; (c) comparing the source program signal to the user selected program signal and, if the source program signal and the user selected program signal differ by less than a predetermined amount, reading the ancillary code from the source program signal.
In accordance with another aspect of the present invention, a method of identifying which of first and second signal sources is supplying a program signal to a monitored receiver, wherein the first and second signal sources and the monitored receiver are located in a household, comprises to following steps: (a) comparing a sync signal from an output of one of the first and second signal sources to a sync signal from an output of the monitored receiver; (b) if the sync signal from an output of one of the first and second signal sources matches the sync signal from an output of the monitored receiver, extracting a reference program signature representative of the output of the monitored receiver and a signature representative of the output of the one of the first and second signal sources; (c) identifying which of the first and second signal sources is a source of the program signal if the reference program signature and the signature representative of the output of the one of the first and second signal sources match; and (d) if the sync signal from an output of the one of the first and second signal sources does not match the sync signal from an output of the monitored receiver, comparing a sync signal from an output of another of the first and second signal sources to a sync signal from an output of the monitored receiver and repeating steps (b) and (c) as necessary.